From 70e22d52bd059d4002e67240edc7e6f761ef5f8d Mon Sep 17 00:00:00 2001
From: Jakob Stornig <jakob.stornig2003@gmail.com>
Date: Thu, 21 Sep 2023 12:59:14 +0200
Subject: [PATCH] (feat) load pgm images

---
 image.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 image.h |  1 +
 2 files changed, 53 insertions(+)

diff --git a/image.c b/image.c
index c35626f..11d7340 100644
--- a/image.c
+++ b/image.c
@@ -12,6 +12,58 @@ void big_endian_to_c_uint(const char * bytes, void * target, int size) {
     }
 }
 
+void read_until_space_or_newline(char * buff, int maxCount, FILE * fptr){
+    int bufferOffset = 0;
+    char c = -1;
+    do{
+        c = (char)getc(fptr);
+        buff[bufferOffset++] = c;
+
+    }while(!feof(fptr) && c != 0 && c != ' ' && c !='\n');
+    buff[bufferOffset-1] = 0;
+}
+
+Image * load_pgm_image(char * image_file_string){
+    FILE * fptr = fopen(image_file_string, "r");
+    Image *image = malloc(sizeof(Image));
+    image->label = -1;
+
+
+    char buffer[100];
+    int magic_number = 0;
+    fgets(buffer, 4, fptr);
+    if(buffer[0] != 'P' || buffer[1] != '5'){
+        printf("Wrong file Format");
+        exit(1);
+    }
+    if(fgetc(fptr) ==  '#'){
+        fgets(buffer, 1024, fptr);
+    }
+
+    int image_width, image_height, image_length, image_white ;
+    read_until_space_or_newline(buffer, 10, fptr);
+    image_width = strtol(buffer, NULL, 10);
+
+    read_until_space_or_newline(buffer, 10, fptr);
+    image_height = strtol(buffer, NULL, 10);
+
+    read_until_space_or_newline(buffer, 10, fptr);
+    image_white = strtol(buffer, NULL, 10);
+
+    image_length = image_width * image_height;
+
+    image->pixel_values = matrix_create(image_height, image_width);
+    for(int i = 0; i < image_height; i++){
+        fread(buffer, 1, 28, fptr);
+        for(int j = 0; j < image_width;  j++){
+            image->pixel_values->numbers[i][j] = (image_white - (unsigned char)buffer[j]) / 255.0;
+        }
+    }
+
+    fclose(fptr);
+    return image;
+}
+
 
 Image** import_images(char* image_file_string, char* label_file_string, int* _number_imported, int count) {
     printf("Loading Images\n");
diff --git a/image.h b/image.h
index 5f146df..6d3caeb 100644
--- a/image.h
+++ b/image.h
@@ -26,6 +26,7 @@ static const int MAGIC_NUMBER_IMAGES = 2051;
  * @return
  */
 Image ** import_images(char* image_file_string, char* label_file_string, int* number_imported, int count);
+Image * load_pgm_image(char * image_file_string);
 void img_print (Image* image);
 void img_visualize(Image*image);
 void img_free (Image* image);
\ No newline at end of file